Should the forward planes be fixed or mobile? I have seen builders do both on this forum.

I was told once long ago that the aft planes really do all of the work. When the tail lifts the nose angles down. This puts the forward planes at a downward angle and the boat moves under the water. So there is no need for active forward planes.

But I see many builders make their forward planes active.

Which is best? For the avid and very active boat driver? Or for the newb? Or for someone who might only get his boat wet for one or two afternoons a year?

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What about the ballast system? I get the feeling that most everyone has moved away from the Propel-powered ballast tanks to a recycling system. With the recycling system your dives are limited to the life left in the battery, right? When the tanks are filled the boat sinks to a state of slight positive buoyancy with "decks awash". Thrust is needed to give the diving planes flow and thus push the boat under water.

Then there is the variable ballast system (whose technical name escapes me at the moment ) In this system a piston alters the displacement of the WTC and thus the amount of water displaced. The boat is able to dive on tanks alone without having to have any thrust from the propeller acting on the diving planes. If calibrated right this system lets the driver "dial in" his depth. The piston moves in x amount and the boat sinks to depth A. The piston moves y amount and the boat sinks to depth B. The only disadvantage to this system would be loss of power or loss of signal. The boat won't naturally surface on its own as with the other system.

Again which is best for the newb, the dabbler or the "professional"?

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I have a friend locally whose students built the variable displacement system in high school shop class. (I think an article was posted to the SCR too. How long ago I don't remember.) It worked very well. My friend said that they left the tank submerged for days and saw little leakage at all.

Thank you for reading my post! Please keep your answers simple please. So far I am an armchair admiral. I am finally building my boat even now. I will need to know whether or not to fix my forward planes or leave them mobile.

Leelan,I am in the same boat as you (pun intended). I have been researching the heck out of it. I think it comes down to this, the best is what you put into it. I will have forward and aft planes working on my first build. For me I see it as allowing the sub to dive evenly instead of having the aft rise up - at least that is what I am thinking, right or wrong that is what will be best for me. As far as ballast system, I am still up in the air. For those more experienced (which is probably most people on this board) it will be dependent on the type of sub and how high you want it to ride on the surface. I am going to build the Revell Gato sub, I think I am going with a WTC gas type ballast system, but I have recently reading about a SNORT system. I would love to hear from some of the others what they prefer and why. I would really be interested to see the plans of the system the students made - maybe I could start a RC club at my school and make kids build ballast systems all year long (add evil laugh here).

What are you going to build?Peace,Tom

If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.

Generally speaking, having both sets of planes working is easier to control, especially on a non-nuke boat. Use the front planes to drive to depth, and the rears on a pitch control to keep the boat level while at depth. And for the best dive, you do want the boat to pitch the bow down to put the forward propulsion to work getting under, as opposed to just the flow over the planes.

If memory serves, you're going with a centerline prop at the rear. Having your rear planes do all the work will get the job done and it will be simplest to implement, but what you'll find is that when you pitch "down", the rear of the boat climbs and will at times pull your prop high enough to the surface to suck in air, reducing thrust and spoiling your dive. Having both sets working helps to alleviate the issue.

As mentioned, the prettiest dive will come from the bow planes pulling the bow under and the rear planes keeping the boat level. Unfortunately what that does is inhibit the ability of your boat to quickly rise or dive, as the rear is in effect counteracting the front. In my scratchbuilt Nautilus, I had both planes connected together and acting with each other (IE: the rear planes go up and the bow planes go down). This gave very quick response to dive commands. Its a trade-off.. more response for quirkier dives.

If you design the boat where the planes can both work, its easy to rig the fronts to work wither with or against the rears. You can just play with it and see what works best. That's the joy of scratchbuilding!

@Leelen - Smack my hand to my forehead - I did not put together that you were putting the Nautilus together. Sorry.@ Bob - I have a noob kind of question, why not have the bow and stern planes both go in the same direction (both going down or both going up instead of one up and one down)?

If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.

Thank you that makes sense! I will apologize in advance for all the noob or beginner or silly or (place your own description here) questions. I am excited to get into this and I am trying to absorb all I can. I am trying to balance the fun of making it a challenge to just get moving!

If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.